Expansible cell for thermostats.



gB/MYA I v J. F. MoBLROY. EXPANSIBLE CELL FOR THBRMOSTATS.

APPLIOATIOI IiLBD APR- 7,;19 06.

- PATENTED DEC. 17, 1907.

. UNITED STATES PATENT oinno'n- JAMES F. MCELROY, OF ALBANY, NEW YORK,ASSIGXOR TO CONSOLIDATED CAR HEATING COMPANY, OF ALBANY, NEW YORK, ACORPORATION OF WEST VIRGINIA.

EXPANSIBLE CELL FOR 'IHERMOS'IA'ITS:

To all whom it may concern: Be f known that I, Jxnns F. lie-E1301,-

a'citizen of the United States, residing at.

Albany, in the county of Albany" and Stateof New York, have inventedcertain new and usefulflmprovements in Expansible Cells for Thermostats,of which thefollowing specification and accompanying drawings illustratethe inventionin a form which I now regard as the best out of the variousforms in which it may be embodied.

This invention relates to the construction of thermostatic cells usedfor steam traps and other purposes and its object is to avoid thehreakages to which such cells are subject.

Of the accompanying drawings: Figure 1 represents a section showing asteam trap of: railway-car .type provided with my improved form of cell,Fig.2 represents a plan view oi the cell, Fig. 3 represents a plan viewof a modified form of the cell, Fig. 4 represents ,a section of thelatter, Fig. 5 represents a sectional View illustrating the action ofthe internal pressure in determining the proper form for the. cell.

The same reference characters indicate the same parts in all the views.

It has been the practice to make thermostatic cells for steam traps inthe form of flexible-walled chambers of flattened circular shape and tofill them with a liquid of low boiling point, such as alcohol, the vaporpressure ofwhich expands the walls of the cell when the latter issubjected to the heat of steam passing through the trap, and this exansion causes a movement of the trap va ve.

. dished diaphragms of sheet-brass or copper to form a pressure-tightchamber containii' g the liquid, and the expansion 'of the cell underinternal vapor-pressure is in reality a distortion caused by the effortof the cell to assume a shape of greater cubical capacity than itsnormal shape, resulting in a separation-of the middle portions ol theopposed Walls or diaphragms.

Heretofore the cells have given much tlOlb ble' by breaking or crackingafter comparatively shortperiods of use, and l. have discovered thecause to consist in a disregard of the proper principles in shaping thecell. Frequently the cells have been made with abrupt bends or folds intheir movable Walls,

The cell is commonly n'iade by ,attachmg together by-their circularedges two Specification of Letters Patent.

"Application filed April 7. 1906. Serial No. 310.406.

produce an internal pressure.

was thatJthe outer or 'uncommed portions Patented Dec. 1 7, 1907.

and often they have possessed an approxijniatelv rectangular form incross-section,

giving a well-marked pivot or hinge-line at the corners, which wouldthen constitute the outer mar ins of the flexible parts of thecellwalls. Whenever such bends or corners exist, the metal will soonbegin to crack at that place, and the cell be rendered useless. Ifbreakagejs to be avoided, there must he no abrupt bends or corners inthat region of the flexible cell-wall which is suhject to the greatestbending movement during the expansion and contraction of the cell in-thecourse of its operation.

In order to ascertain the proper cross-sectional form for the cell, Iperformed the. experiment of making a cell with very thin and veryflexible metal walls, l'illing it with the usual liquid and scaling it,conliniug it between resistance pieces to substantially duplicate itssituation in a steam-trap, and then subjecting the cell to heat in orderto The result assumed a shape substantially circular in cross-sectionaloutline, as indicated in Fig. 5, where 10 represents a cell supposed tohave Walls of perfectflexibility,and 1]. 12. the upper and lowerresistance pieces. This action can be'explained from the fact that theinternal pressure, which is exerted radially. in all directions, tendsto impart the circular form, namely that form which possesses thegreatest area f or any given circum- 'l'erence.

n putting Ll above principles into practice make the actual cell asshown in Figs. 1 and 2, for example, of the same cross-sectional outlinein its marginal or unconfined part as a cell. of perfectflexibility andcorresponding dimetzi 3 wo d tend to assume under internal pressure,nan'i'ely an approximately ciircular outline. In Figs. 1 and 2, 10 isthe cell composed of upper and lower circular dished diaphragms 13, 14,headed and soldered together at their edges 15. 12 is the lowerresistance piece or seat for the cell, fixed to the trap casing, and 11is the upper resistance piece :o1'istitut.ing a follower attached to thestem of the trap valve 16. The resistance pieces may either rest in thelowest hollows of the diaphragrns as seen in Fig. 1 or the diaphragms,shown in Figs.

-3 and 4. mayhave raised flat central portions by Letters Patent is:

17 for contact with the resistance pieces; In both cases it will be seenthat the cross-sectional outline of the two diaphragm-margins takentogether conforms substantially to the greater or major arc of thecircle.

The above-described diaphragms are free from permanent folds,corrugations or cor ners in the marginal portions subject to thegreatest bending in operation, and the actual flexure which takes placeis distributed throughout a large area and not confined to anyWell-marked line or lines. Consequently 1 ernature breakage and crackingare'prac tically eliminated. Y

WVhat'I claim as new andclesire to secure 1. Athermostatic cell forsteam traps or other controllers comprisinga sealed flexible metalcasing of flattened form containing a liquid and having walls with idecentral seats on opposite sides for -abutting the re I sistance piecesof the trapor other controller of'perfectflenihil'ity would tend tocomposed of t-tvs o flexible metal diephrag tr'a and a marginal flexingortion free froin'a'imrupt bends and of su s-t'antlallysectlonalouthnewhich a correspond].

under the influence cf internal 'x essnre; Q 2. Asealedtherlhostaticcell'containirs" liquid of low boilingpoint and having freefrom abrupt bendsin their flex ng per tions and connected by theiiedges'; said (lia hragms having substantially-flat cenportions andhaving marginal portions which together conform substantially to themajor arc of a circle.

'In testimony whereof Ihave hereunto setmy hand in the presence of twosubs'cribing Witnesses, the 3rd day of April 1906. I

JAMES ,F. LICELROY. Witnesses:v

' .BEULAH CABLE,

ERNEST D. JANSEN.

